This invention relates to down-hole pump operation, and more particularly relates to computer systems for optimizing down-hole progressive cavity pump operation during oil and gas recovery.
It is well known in the art that downhole pumps are commonly used to provide supplemental or artificial lifting action to deliver fluids from subsurface formations to the surface of a producing well after reservoir pressure has waned to the extent naturally-available energy is insufficient for production purposes. Accordingly, it is common practice for downhole pump assemblies and associated pump control systems to be used to transport fluids stored in oil and gas wells to the earth's surface.
For example, in U.S. Pat. No. 5,193,985, Escue et al. teach a pump control system having a surface monitoring station for sustaining radio communication with downhole motor-pump assemblies. A plurality of sensors incorporated into each downhole motor-pump assembly send corresponding signals indicative of such variables as temperature and fluid levels for monitoring well and pump conditions. The Escue disclosure elucidates that prior art pump control systems typically monitor minimal variables which have been inadequate for effectively identifying the panoply of pump malfunctions which have adversely affected well production.
For effectively operating downhole pumps, particularly progressive cavity pumps, during oil and gas recovery, it is imperative that the dynamic pumping fluid level be known. As is well known to those skilled in the art, dynamic pumping fluid level shows the relationship between pumping rate and well productivity, which, in turn, indicates to oilfield practitioners actual well performance. Thus, knowledge of dynamic pumping fluid level provides insight into well productivity, completion, and reservoir condition. Furthermore, comparison of the actual value for a well's dynamic pumping fluid level with theoretical pump output capacity provides crucial insight into the condition and performance of the well's pump system.
As will be readily understood by those skilled in the art, a pump loses efficiency as its various components wear out. During conventional oil well recovery operations, adjusting pump output, which is accomplished by manually adjusting the pump's RPM, is prerequisite to maintaining maximum well productivity. As will be appreciated by those skilled in the art, with no real-time knowledge of well conditions, analysis of well and pump performance is not only limited by lack of timely information, but also is time-consuming and time-intensive. Unfortunately, without automated real-time analysis, catastrophic reduction of well production is the only way to observe changes pertaining to requirements for pump performance.
Heretofore in the art, a well operator must use a periodic expensive and inconvenient sonic fluid level testing to obtain dynamic fluid level. It is common practice, however, due to the inconvenience and expense of these sonic fluid tests, for well operators to estimate the required production rate--and concomitant pump performance--as an attempt to attain maximum well productivity. However, there is a serious risk of excessively low fluid levels will seriously damage an oil well's productivity and also causing damage to pumping equipment. To avoid such risk that potentially disastrous conditions and consequences will occur, operators frequently take conservative actions, thereby correspondingly reducing the probability of achieving maximum oil well production.
As will be appreciated by those skilled in the art, pumps are used in gas wells to remove fluid from the well bore, thereby relieving back pressure on the formation. Such back pressure produced by fluid accumulated downhole, of course, reduces or may even terminate gas well production. These pumps are usually placed by operators below the well perforations, and fluid level is reduced until gas flow out of the well resumes. Typically, gas flow emanating from a gas well will continue until back pressure recurs due to continuing fluid inflow into the well.
Thus, it should be evident to those skilled in the art that, by automating a downhole pump system and providing continuous analysis of well bore and pump conditions, increased gas and oil production of a well heretofore unknown in the art may be attained. Additional benefits include increased life span of pumps and wells and cost reduction attributable to optimized well production and significantly reduced service requirements. Furthermore, the availability of such an automated computer system would also assure that optimum longevity and performance be obtained from pumps used in the progressive cavity pumping applications and the like. Of course, the concomitant advantages pertaining to reduced labor costs and increased production performance of the oil or gas well are self-evident.
It is common knowledge among oilfield production and automation engineers involved in progressive cavity pump systems and the like that there is inherent difficulty associated with effectively automating such pump systems under a real-time closed-loop optimization protocol. Not only is the prerequisite data collection instrumentation cost-prohibitive, but also the information provided by this collected data must be processed and completely analyzed to assure that comprehensive optimization is practicable. Such an oilfield automated pump system has been heretofore unknown in the art. Indeed, attempting to construct such a system using currently available instrumentation generally necessitates a practitioner setting pressure sensors at the pump suction and discharge. This approach for attempting to automate downhole pump systems is evidently expensive and mechanically-elusive because the pump components being controlled are located downhole.
Accordingly, these limitations and disadvantages of the prior art are overcome with the present invention, wherein a computer system is provided that is particularly useful for enabling progressive cavity pumping operations during oil and gas oil well recovery to be monitored and analyzed in real-time, wherein production may be optimized. The pump system taught by the present invention provides oilfield production and automation engineers with a cost-effective comprehensive analytical and automation tool.